Machine for generating gears



Sept. 20, 1960 o. w. UFERT MACHINE FUR GENERATING @BARS 5 Sheets-Sheet l Filed Aug. 9, 1954 sept. 2o, 1960 o. w. UFERT 2,953,067

MACHINE FOR GENERATING SEARS Filed Aug* 9, 1954 5 Sheets-Sheet 2 fz/ MM Sept. 20, 1960 o. w. UFERT MACHINE FOR GENERATING GEARS 3 Sheets-Sheet 3 United States Patent O MACI-IDE F OR GENERATING GEARS Otto Wilhelm Ufert, Dusseldorf-Oberkassel, Germany,

assignor to Schiess Aktiengesellschaft, Dusseldorf- Oberkassel, Germany Filed Aug. 9, 1954, Ser. No. 448,674

Claims priority, application Germany Aug. 12, 1953 8 Claims. (Cl. 90-1.6)

The present invention relates to a machine for producing gears. Such machines have been provided with means for mounting a swivel-type shaving head on a plate, the top portion of which is interchangeable, the shaving head being radially adjustable in relation to the work piece. This is very expedient inasmuch as the top part of the tool support of a gear hobbing machine can always be swiveled around an axis which is vertical to the axis of work. Therefore, the means for swivelling the shaving head, i.e. the circular guideways, the means for centering and the fastening members to be arranged in the annular grooves are already present. In addition, thereto, attachments are also avilable which permit a power operated movement of the plate in the direction of the axis of the work piece, which usually are a guideway on the column on which the plate moves in longitudinal direction, and a screw spindle with nut, the axis of which is parallel to the axis of the work piece. Therefore, a gear bobbing machine usually incorporates already all such features as are required to permit the shaving head to perform its movements and to enable it to be accurately set relative to the work piece,

The bobbing feed screw spindle and the guideway on the column for the plate may, however, be regarded to be two of the most important machine members which will greatly influence the accuracy of the work since any inaccuracy in the pitch of the feed screw will have some unfavorable effect on the accuracy of helical gears to be cut in conformity therewith. Any partial, unilateral or uneven wear of the plate guideway will result in errors in the pitch of the work gear and also in the longitudinal direction, which will at least be as big as the error in the guideway since, when bobbing, the play between guideway and plate will result in vibrations which will still be increased at a certain resonance.

An object of this invention consists in some further improvement and development of machines for shaving the anks of gear teeth by means of a gear-like cutter on a gear hobber. This object has been materialized according to the present invention by mounting on the tool carriage or support a swivel-type shaving head in lieu of the bobbing head in such a manner that the shaving bead is radially adjustable in relation to the work gear and is vertically movable on a guideway parallel to the hobbing feed guideway, so that the shaving head can be moved in the direction of the axis of the work piece, in two ways, namely first by moving the shaving head on the shaving head guideway and secondly, by moving the tool support on the bobbing feed guideway.

It is also an object of this invention to limit the stroke of the shaving head on the shaving head guideway over the stroke of the tool saddle on the bobbing feed guideway. The shaving head guideway is supported on the tool support to such an extent that even with the shaving head in its end positions, no tilting forces whatsoever resulting from the shaving pressure will act on the attachment. Due to a special design, the shaving bead can be Hice moved by means of a shaving feed gear unit which is fully independent of the bobbing feed, and the shaving feed gearing can be driven by a separate motor which is independent of the bobbing feed drive.

Due to the design of the machine according to the invention, no wear at all will occur at the bobbing feed screw and bobbing feed guideway while shaving (these two machine parts being most important for an accurate operation 4of the machine when bobbing the gears) since the tool support will not move at all when shaving. Thus the vibrations of the tool support in case of an unevenly worn bobbing feed guideway and the much feared resonance vibrations are eliminated. In addition thereto, the tool support is clamped to the guideway so that it is practically integral with the column.

Due to the fact that the tool support is stationary during the shaving operation, it is merely necessary to move the relatively small and light members of the shaving attachment in the direction of the work axis which will require a small feed drive only. The feed motor for the shaving attachment is, therefore, much smaller, lighter and lthus more economical than the heavy saddle feed motor with its high power consumption. The invention is applicable without necessitating any change in the column of the gear hobber, the tool support and all feed and drive elements for the support, thereby avoiding the high cost of manufacturing the large and heavy machine parts required in case of a dual-type machine or if the standard machine is converted into a gear hobber with dual drive for the support. In accordance with the invention, the guideway of the shaving attachment may also be kept shorter than the bobbing feed guideway as, in spite of its shorter guideway, the shaving head can be raised and lowered to any height of the work gear due to the two movements described above. Due to the fact that according to the invention, the shaving attachment can be brought to any height together with the tool support and that only the shaving feed motion proper is performed on the guideway of the attachment, the guideway can be utilized to its full length and even in the case of narrowfaced gears uneven wear is avoided if the support is gradually lowered or raised on the bobbing feed guideway, thus altering the position of that portion of the shaving head guideway on which the shaving head moves to and fro when shaving the gear.

The invention is illustrated by way of example in connection with the accompanying drawings, in which Fig. l shows a diagrammatic side view of a gear hobber with the work gear clamped in position;

Fig. 2 shows on a larger scale than that of Fig. l the side view of a shaving attachment mounted in conformity with the present invention on the tool support of the gear hobber in lieu of the bobbing head.

Fig. 3 shows the front view of a gear hobber wit-hout workpiece; v

Fig. 4 shows an enlarged View of a detail of Fig. 3;

Fig. 5 shows the front View of a shaving attachment mounted on the tool support in lieu of the bobbing head.

As shown in Fig. l, the gear blank W is clamped on the table 10 of a gear bobbing machine. The table lll rotates on the base 11. The base 11 is connected to the bed 12 of the machine, the bed carrying the column 13 which is radially adjustable in relation to Ithe gear blank W to be machined. The column 13 is provided with a vertical bobbing feed guideway 16 on which the tool carriage or support 14 moves parallel to the axis A of the work gear W. A removable bobbing head 15 with the cutter F is mounted on the tool support 14. When raising or lowering the support 14, both the bobbing head 15 and the tool support 14 will perform the bobbing feed motion in theY direction of axis A of work gear W,

. n i u Y Y 3Y soithat rwhen hobbing, the tooth spaces are gradually cut on the enti-re face width of the gear blank, finally producing theV gear.

The hobbing head is mountedk on theV tool support Y spindle 17 inside the column 13 and a screw nut (not shown) Von the Vtool support V14. The feed is derived from the main motor 1S through various gearing elements which are not shown in detail and which are mainly accommodated inside the Vgear box 19.

After the hobbing operation has been completed, gear W remains clamped to the table 16 forrshaving the teeth. The hobbing head 15 only is removed andareplaced by a guideway head 20 (Figs. 2 and 5)Yfor the shaving head 21 which is screwed on to the tool support 14 in a posi- Vtion parallel to the bobbing feed guideway 1-6,l so that the work gear W can be shaved `on the gear hobber immediately after bobbing.

The shavingY head 21 carries the gear-like rotary shaving tool S as in conventional gear shaving machinery Without any separate drive, since it =will rotate due to being in mesh with the revolving gear W which isv to be shaved.

Y The shaving head 21 can be swiveled. on a setting slide 22 around an axis 23 which lies in about the center ofthe rotary cutter. By moving the setting slide -22 on an inclined guideway 24 for tool setting purposes, the head 21 can be radially adjusted in relation to the work gear W. The inclined guideway 24 is arranged on the top Y surface of a shaving slide 25 which headl guideway 20. Y

The `top and bottom position of the swivel axis 23 of the shaving head Y21 is shown by dot dash lines 23', 23" in Fig. 2. The maximum travel of the shaving head 21V on the shaving head guideway 20 is marked a and is smaller than travel b of tool supportv 14 on bobbing feed guideway 16, the end positions 14', 14 of the'supmoves on the shaving;

be evenly reduced on all tooth anks when having the teeth, the tooth anks are smoothed over the entire circumference, the surface becoming denser and thus more resistant to wear. FinallyY the output ofy the machine can be increased when hobbing, as the hobbing feed may be increased. This is due to the fact that with gears which are not finished by shaving, the feed rate permissible is dependent upon the condition, i.e. roughness, of the surface which is produced by the bobbing feed. Subsequent shaving of the Work gear on the Vsame machine without resetting the job using an Vattachmentvwhich prevents an additional or unequal lwear of the machine, will smooth out and eliminate respectively such roughnessY on lthe entire face Width, so that the hobbing feed may be increased. In this connection it maybe mentioned that the shaving slide 25 is preferably fitted with adjustable gibs to ensure a running of the slide on the guideWay 20 v free from any play. In Vaddition thereto, the table track i subsequent shaving: Va rotatable table for receiving a gear blank to be hobbed, supporting means supporting said table, a vertical column movable selectively toward.V and away fromrthe axis ofrotation of said table along a Y vertical plane passing throughV said column and said axis,

port being shown in Fig. 1 by dot dash lines. The shaving head guideway 20 is supported on theftool support 14 over such a lengthV c that the shaving pressure whichV is approximately in the cutter center cannot produce any tilting forces upon the shaving head 21,V the setting slide 22 and the shaving head guideway 20. The shaving head 21 is moved -on the shaving head guideway 20 by means of the shaving slide 25 through a small motor 27 (Fig. 5) -fwhich is preferably mounted on top ofthe shaving head guideway 20 and which operates the shavingV head 21 independently of the hobbing feed, through a bevel gear driven reduction gearing 37, 38 and a screw'spindle Y28 (Fig.5).V Y Y 'Y While for `cutting gears the table 10 is rotated slowly and steadilyV orv step by step in the well-known manner through an index worm gearing 29 30 (Fig.V l),A the worm 29 is brought out of mesh with the worm wheel 30 in case of shaving and the table 10 is driven by a powerful `motor 32 (provided for, table driveV only) through the gear unit 33, 34'35 at such 'speeds as are said columnbeing provided with vertical guiding means,`

a tool slide reciprocably mounted on said guiding means for movement parallel to the axis of rotation .of said, table, a first drive drivingly connected to saidl tool slide for reciprocating the same, an auxiliary guide member detachably connected to said tool slide, an auxiliary slide slidably mounted `on said auxiliary guide member for andl driving means including a first motor anda dividing fthe auxiliaryy guide member is'supported Vby said tool. Y

worm Wheel for rotating saidY table at a Vfirst speed for hobbingsaid driving ymeans being adapted selectively to be drivinglyV disconnected fromV said table, and' a'second motor independent of said first motor and adapted selec tively to be drivingly connected to said table for driving said table at a second elevated speed forpshaying.

y 2. An arrangement according to claim l,- in which.

p slide over an area suicient to prevent said auxiliary guide Y' member from exerting any tilting forces on e saidr tool slide.V Y

3. An arrangement according to claim; l, in which the Y maximum stroke of said auxiliary slide, is limited over required "to give the work gear W to be shaved a circumferential speedof approximately 100 m./min; The

tangents of the true involute of rthe tooth profile, which are positively produced when hobbingwill be evenly regear which were caused by the bobbing operation will means,a tool slide reciprocably mounted on said the maximum stroke `of said toolslidefy f `4. In a machine for producing gears by hobbing and subsequent shaving; a Vrotatable table for receiving a gear blank to bev hobbed, supporting means supporting said table, alvertical column movable selectively toward and away from the axis oflr'otation of said tableV along a vertical plane passing through said column andY 'said' axis, said column being provided-with verticalY guiding ing means, firstv motorV means, meansrdrivingly connecting said first motor means 'to said tool slide and said table for'respectively reciprocating saidtool slide along al path parallel' to the axis of rotation `of said table and for rotating said table at a rst speed for hobbing, said iirst motor means being adapted selectively to be drivingly disconnected from said table, said tool slide being arranged selectively and detachably to receive a hobbing head and in substitution therefor an auxiliary guide member with an auxiliary slide for receiving a shaving head, said tool slide also being adapted to be stationarily connected to said column, second motor means independent of said rst motor means and supported by said auxiliary guide member for driving said auxiliary slide, and third motor means independent `of said rst and second motor means and adapted selectively drivingly to be connected to said table for driving the same at a second speed higher than said rst speed for carrying out a shaving operation.

5. A shaving unit for use in connection with a hobbing machine having a base With a bed, a table rotatably mounted on said base for supporting a gear blank to be hobbed, a column slidable on said bed for adjustment relative to said table, a tool support movably mounted on said column in a direction substantially parallel to the axis of rotation of said table, and spindle means for eecting the hobbing feed vof said tool support during the hobbing operation, said shaving unit including: a main support detachably connectable to said tool support and provided With guiding surfaces substantially parallel to the axis of rotation of said table, a slide slidable on the guiding surfaces of said main support, a shaving head carried by said slide, said slide and said shaving head including means for bringing about movement of said shaving head in a direction perpendicular to the path of movement of said slide on said main support, driving means carried by said shaving head for actuating the latter to bring about a shaving feed movement independent of the actuation of said spindle means, and gear means drivingly connecting said driving means to said slide for actuating the same.

6. An arrangement according to claim 5, in which said driving means includes a feed spindle, and motor means drivingly connected to said slide for feeding the same during a shaving operation.

7. An arrangement according to claim 5, in which said slide is supported by said main support over an area suicient to prevent said slide from exerting a tilting force on said main support with regard to said tool support.

8. An arrangement according to claim 5, which includes means for limiting the maximum stroke of said slide over the maximum stroke of said support.

References Cited in the tile of this patent UNITED STATES PATENTS 1,211,183 Kulenkampf Jan. 2, 1917 2,227,491 Drummond Ian. 7, 1941 2,383,753 Wallace Aug. 28, 1945 2,452,520 Falk et al. Oct. 26, 1948 2,504,968 Eklund Apr. 25, 1950 2,553,984 Siekmann May 22, 1951v 2,556,142 McLeod June 5, 1951y 2,556,143 McLeod June 5, 1951 2,556,318 Cooper June l2,- 1951 2,749,802 Carlsen June 12, 1956 FOREIGN PATENTS 128,205 Sweden May 9, 1950 830,843 ,Germany June z5. 19.53 

